This invention relates generally to dynamoelectric machines and more particularly to a stator and fan for a dynamoelectric machine.
Dynamoelectric machines, in the form of electric motors, have numerous applications, such as for washing machine and compressor motors. An important part of the utility of the motor is that it can be manufactured inexpensively and yet provide a reliable, long lasting, quiet, low maintenance engine for an appliance or other machine. Thus, there is a need for a motor which can be easily and rapidly assembled without sacrificing quality and reliability. One source of delay and cost in the manufacturing process is the electrical connections which must be made in the motor. Electronically commutated motors have leads from the windings connected to one or more circuit boards which mount control and power circuitry for energizing the windings. Typically, crimp leads are attached to the magnet wires and a connector block or other suitable connector is mounted on the circuit board. The crimp leads are then attached to the connector block on the circuit board. These connecting steps require significant time to carry out during the assembly process. In addition, the circuit board itself must be mounted on the motor housing which requires fastening steps, also taking time to accomplish.
In addition to making the connection of the winding leads, it is necessary to position a sensor, such as a Hall device, for detecting the position of the rotor and making the appropriate electrical connections to the circuit board. A Hall device must be at least partially located between the stator and the rotor in the air gap. The air gap is as small as practicable so the Hall device must be precisely and securely located to avoid being hit by the rotor as it turns. Moreover, it is necessary that the circuit board be electrically insulated from the windings (other than where the windings are attached to the circuit board) and the motor housing. However, there is a need to be able to accomplish the insulation rapidly without employing additional motor components.
Another aspect of motor operation is that circuit board and windings need to be cooled during operation. In order to remove heat a fan can be attached to the rotor shaft to rotate with the rotor and move air through the motor housing. However, a fan generates mechanical noise which detracts from the otherwise quiet operation of the motor. The rotor usually turns at very high speed (e.g., 16,000 rpm), at least in one direction. The high speed exacerbates the problem of fan noise.